Solid-state reactive diffusion between Ni and W

► The solid-state reactive diffusion between Ni and W was observed at temperatures of 1023-1173 K. ► During annealing, the Ni4W layer is formed at the Ni/W interface, and the DIR region is produced at the Ni4W/Ni interface. ► The growth behavior of the DIR region was numerically analyzed using the new extended-model. ► Within the experimental annealing times, the growth of the DIR region is controlled by the interface reaction and the boundary diffusion.